Which statement is true about water molecules?
a. The oxygen atom has a negative charge.
b. The hydrogen atoms do not share electrons.
c. Water molecules move randomly around each other.
d. Water molecules cannot dissolve many substances.
How does water relate to the ability of a living thing to generate energy?
a. Water is responsible for the generation of energy in the cell.
b. The cell is an aqueous environment.
c. Without the proper balance of water, chemical reactions in cells could not take place.
What is the most important role of hydrogen bonding between water molecules?
a. It enables water molecules to bond to each other.
b. It allows oxygen and hydrogen atoms to be charged.
c. It allows cells to keep water in balance.
The Correct Answer and Explanation is:
1. Which statement is true about water molecules?
Correct Answer:
a. The oxygen atom has a negative charge.
Explanation:
Water (H₂O) is a polar molecule, meaning it has distinct positive and negative ends. The oxygen atom in a water molecule is more electronegative than the hydrogen atoms, meaning it attracts electrons more strongly. This results in the oxygen atom carrying a partial negative charge, while the hydrogen atoms carry partial positive charges. The unequal sharing of electrons makes water a polar molecule, which is crucial for its unique properties.
- b. The hydrogen atoms do not share electrons is incorrect because the hydrogen atoms do share electrons with oxygen to form covalent bonds.
- c. Water molecules move randomly around each other is incorrect because while water molecules move randomly, they also exhibit specific behaviors due to hydrogen bonding, which gives water its structure and properties.
- d. Water molecules cannot dissolve many substances is incorrect because water is known as the “universal solvent” because it can dissolve a wide range of substances due to its polarity.
2. How does water relate to the ability of a living thing to generate energy?
Correct Answer:
c. Without the proper balance of water, chemical reactions in cells could not take place.
Explanation:
Water is essential for life because it provides the medium in which biochemical reactions occur. Many of the chemical reactions that produce energy in cells, such as cellular respiration and photosynthesis, occur in aqueous environments. Water helps to dissolve necessary substances, enabling the movement of ions and molecules across membranes and facilitating metabolic reactions.
- a. Water is responsible for the generation of energy in the cell is incorrect because while water is crucial for enabling reactions, it doesn’t directly generate energy.
- b. The cell is an aqueous environment is true but does not fully explain the relationship between water and energy generation.
- c. Without the proper balance of water, chemical reactions in cells could not take place is the best answer because water is crucial for maintaining the environment needed for energy-producing reactions in cells.
3. What is the most important role of hydrogen bonding between water molecules?
Correct Answer:
a. It enables water molecules to bond to each other.
Explanation:
Hydrogen bonds are weak attractions between the positive hydrogen atom of one water molecule and the negative oxygen atom of another. This type of bonding is responsible for many of water’s unique properties, such as its high surface tension, high boiling and melting points, and the ability to form liquid at room temperature. These bonds enable water molecules to stick together, contributing to phenomena like capillary action and surface tension.
- b. It allows oxygen and hydrogen atoms to be charged is incorrect. The charges on oxygen and hydrogen atoms are partial, not full charges, and the hydrogen bonds are due to these partial charges.
- c. It allows cells to keep water in balance is true in a sense, but the primary function of hydrogen bonding is to allow water molecules to bond to each other, facilitating water’s cohesive and adhesive properties.